----------------------------------------------------------------
EXPLANATION OF CONSOLIDATED LUNAR ATLAS -- LTVT CALIBRATION DATA
----------------------------------------------------------------

This folder contains LTVT calibration data for the Oblique and Full Moon photos in the on-line version of the 1960's /Consolidated Lunar Atlas/:

http://www.lpi.usra.edu/resources/cla/

The calibration data allows the photos to be searched through, loaded and analyzed with LTVT.  For this to work, three requirements have to be met:

1. You must have copies of the same photos, with the same names, as those that were calibrated.

2. The photos must be located in the directory locations specified in the file, *or* you must edit the file so the calibration data points to the directories where they *are* located.

3. Once Conditions 1 & 2 are satisfied, you must tell LTVT to read the calibration data.  This can be done either by changing the External File Associations *or* by using Notepad to add the present lines to the normal photo calibration file.


== Condition 1:  What photos were calibrated? ==

a. For the "Low-Oblique Photography," the frames calibrated are the "Hi-resolution TIFF, Full Frame" views, converted to JPEG format.  In other words, for Oblique Section A1 you need to go to:

http://www.lpi.usra.edu/resources/cla/info/a1/

and download the Full Frame TIFF file (2.8 MB).  Then you need to convert it to a JPEG format using something like Photoshop or the Window Image Previewer.  Finally the name of the saved file should be "a1.jpg".

If you have many TIFF files it is possible to mass convert them to JPEG with something like Irfan View:

http://www.irfanview.com

b. For the "Full Moon Photography" the photos calibrated are the "Hi-resolution JPG, Full Frame" images. For example, for Section Aii, go to:

http://www.lpi.usra.edu/resources/cla/info/aii/

and simply use the link below the preview photo to download to disk the 2.1 MB JPEG file.  Be sure to save this as "aii.jpg".


== Condition 2: Placing the Photos in an Accessible Location ==
	
The calibration file in this folder is called "CLA_calibrations.txt".  It can be opened with any simple text processor, such as Notepad.  If you do so, you will see that the folder where LTVT is told to look for the files is:

C:\CLA\

You need to either create a folder with *exactly* this name and place the JPEG photos in it;  or else you need to edit "CLA_calibrations.txt" so that the correct directory is indicated.  If you edit the file, you can specify *any* directory, even on an external or removable drive.


== Condition 3 : Telling LTVT to read the calibration file ==

There are two methods for making the calibration data visible to LTVT:

a. Use "Files...Change External File Associations..." to select this file as the "Calibrated Photos" file.

b. Use Notepad to copy and paste the information from "CLA_calibrations.txt" to the end of the file you normally store calibration data in -- typically "PhotoCalibrationData.txt".


-----------------------------------------------------------

Once the three conditions have been satisfied you should be able to effortly access the Consolidated Lunar Atlas photos through LTVT.  

If an area of interest is displayed on the screen, you should be able to simply click "Find Photos" in the lower right of the LTVT main window, and you should then see a list of the CLA plates that include that area, ranked by descending sun angle.

Typically you want to load the selected CLA plate in the "Sun angle" (only) mode.  In that mode, the present screen will be repainted with the CLA data, but without any change in size or pointing. Because the sun angle has been updated you will be able to make measurements, including heights from shadow lengths, on the CLA photo.

Note: even if there is problem with accessing the photos (for example, wrong file names or wrong directory location), the FIND PHOTOS button should still give you a list of all the CLA photos including the present region, and the sun angles at which they were taken  you just wont be able to see the photo.

-----------------------------------------------------------


-- Jim Mosher, June 5, 2008


